The Białowie_ za Forest (BF) is an extensive and relatively little changed forest complex on the PolishBelarussian border. Data on the structure and diversity of its breeding avifauna have mostly been collected in primeval old-growth stands, preserved within the Białowie_ za National Park (BNP). Mapping censuses repeated in space (plots, replicated in riverine, oak-limehornbeam and coniferous stands) and time (permanent plots, 28 years) reveal that the breeding bird assemblages are rich in species (29-52/season in a 25 to 33-ha plot), but of moderate overall density (40-120 pairs/ 10 ha). The latter is due to low, lower than in mantransformed areas, densities of the majority of particular species. Despite marked changes in vegetation structure, the composition of the breeding bird assemblage does not vary much across different primeval forest types, with a single breeding bird community inhabiting all of them, including treefall gaps. High richness of the BF avifauna stems from the Forest's geographical locality, as well as from a high level of the primeval avifauna retention. Over 95% of the 135-140 pristine species still breed there. Especially species-rich groups are birds of prey, owls, woodpeckers and Sylvinae warblers. Bird communities in the BNP and primeval tropical rain forests share many features, suggesting that natural differences between temperate and tropical forests were less pronounced in the past. The combination of high species richness with low densities of individual species is probably a feature of all pristine forests, independent of climatic zone. The BF avifauna must once have been typical of the ancient European forests and it has become so exceptional chiefly because it has preserved most of its pristine features. The BF thus constitutes an indispensable reference site for future studies of woodland bird biology. To ensure its survival should become a priority. Commercial logging, taking place over 80% of the Polish BF part, severely changes the Forest's structure and strongly affects the birds, especially species which depend on dead wood (Dendrocopos leucotos, Picoides tridactylus) and on old-growth stands. The small area protected as the BNP becomes an increasingly isolated ''island'', in which preservation of the primeval forest features seems to be impossible. In order to retain them, it is necessary to protect the whole BF area.

Aim Despite the increasing pace of urbanization, little is known about how this process affects biodiversity globally. We investigate macroecological patterns of bird assemblages in urbanized areas relative to semi-natural ecosystems.Location World-wide. MethodsWe use a database of quantitative bird surveys to compare key assemblage structure parameters for plots in urbanized and semi-natural ecosystems controlling for spatial autocorrelation and survey methodology. We use the term 'urbanized' instead of 'urban' ecosystems as many of the plots were not located in the centre of towns but in remnant habitat patches within conurbations.Results Some macroecological relationships were conserved in urbanized landscapes. Species-area, species-abundance and species-biomass relationships did not differ significantly between urbanized and non-urbanized environments. However, there were differences in the relationships between productivity and assemblage structure. In forests, species richness increased with productivity; in both forests and open habitats, the evenness of species abundances declined as productivity increased. Among urbanized plots, instead, both species richness and the evenness of species abundances were independent of variation in productivity. Main conclusionsRemnant habitats within urbanized areas are subject to many ecological alterations, yet key macroecological patterns differ remarkably little in urbanized versus non-urbanized plots. Our results support the need for increased conservation activities in urbanized landscapes, particularly given the additional benefits of local experiences of biodiversity for the human population. With increasing urbanization world-wide, broad-scale efforts are needed to understand and manage the effects of this driver of change on biodiversity.

Wesol owski, T. and Tomial ojć, L. 2005. Nest sites, nest depredation, and productivity of avian broods in a primeval temperate forest: do the generalisations hold? Á/ J. Avian Biol. 36: 361 Á/367. Data on nest success and brood productivity of three ground-nesting, three canopynesting and four hole-nesting (non-excavator) passerines were gathered in a primeval lowland temperate forest (Bial owieża National Park, E Poland). Natural holes were superabundant and the birds had to cope with a heavy pressure of a diverse assemblage of nest predators. We tested whether in such conditions nesting in holes is more productive, and whether nesting on the ground is most risky, as expected from some earlier generalisations. The nesting success varied significantly across the nest types. As predicted, the success of hole-nesters (51 Á/74%) and their brood productivity were the highest. Contrary to expectations, the ground-nesters (27 Á/40%) did not breed less successfully than the canopy-nesters (22 Á/33%). Nest predators, responsible for 64 Á/ 94% of nest losses in individual species, were the major cause of the differences among nest types. The Bial owieża results confirm the long-held view that holes tend to be the safest breeding places, but lend no support for the idea that nesting on the ground is more dangerous than in tree crowns.T. Wesol owski (correspondence),

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